1. Field of the Invention
This invention relates to a device for aligning coiled sheet material being fed to a die of a power press during stamping operations.
2. Description of the Prior Art
In the production of work pieces from coiled sheet material, such as coils of sheet steel, the coil is normally placed in a cradle and predetermined lengths of this coil of sheet material are intermittently advanced into a power press. The problems associated with control of the forward advancement of the sheet material have been largely overcome by modern feeders such as that described in U.S. Pat. No. 3,771,703. These feeders utilized gripping rollers between which the sheet material is pinched with the rollers preferably being powered by hydraulic motors.
A typical power press is a frame structure which provides a feed path for the sheet material between relatively moveable tool-carrying members so that the tools or dies carried by the latter can act on the sheet material to form the work pieces. One of the tool-carrying members is normally in the form of a ram moveable rectilinearly along a guide path in a direction toward and away from another tool-carrying member forming a bed on the frame structure. The drive means for the ram normally comprises the flywheel operatively connected through a clutch with an eccentric element such as crank, cam or eccentric serving to impart the required movement to the ram.
It will be appreciated that in order to pull sheet material through the feeder in an accurate manner, there must be a very large pressure on the gripping rollers of the feeder. Moreover, if the sheet material is not well centered in these rollers and equal pressure applied across the sheet material, there is a tendency for corrugations to form along the edges of the material. Moreover, it is both difficult and time consuming to try to align the die of the power press completely accurately with the feeder, with the result that frequently there is a small degree of non-alignment which again causes deformation of the edge of the sheet material. When this occurs, it may be necessary to shut down the system and attempt to do further realigning manually until no further indications of non-alignment are in evidence.
Another situation which normally creates problems is where the steel from the rolling mill or slitting mill contains a camber, i.e. a deviation from straight line. Here again it becomes necessary to shut down the system and try to make adjustments so that the alignment will be proper to take into account the camber and thereby avoid damaging the edges of the sheet material.
It is therfore, the object of the present invention to provide a system to automatically adjust the alignment of the feeder so that the sheet material at all times will be in full alignment within the press.